Triangle facts
Sides and angles in; area, radii and centres out.
For checking your work after you’ve tried it yourself.
Step 1: Choose what you know
Choose what you know
Three sides, two sides and an angle, two angles and a side, or three points.
Step 2: Type the values
Type the values
Angles in degrees.
Step 3: Read the facts
Read the facts
Then open Do it by hand.
What it does.
Works out everything about a triangle from enough information: every side and angle, the area, perimeter, inradius, circumradius, heights, medians and angle bisectors, and, from three points, the four classic centres. It draws the triangle to scale.
When it helps.
Checking measurements you worked out with the cosine rule, Heron's formula and the like.
What it won’t do.
Answers are decimals rounded to 6 significant figures, not exact forms.
Example.
Sides 3, 4 and 5 make a right-angled triangle with area 6.